Compact manual transaxle

ABSTRACT

A compact manual transaxle includes an input shaft having five fixed input gears, a first intermediate shaft rotatably supporting four speed gears meshing with four of the input gears, a second intermediate shaft rotatably supporting a speed gear meshed with the other input gear and a reverse gear meshed with a speed gear on the first intermediate shaft, and a differential. A transfer gear on each intermediate shaft is meshed with a final drive gear fixed to the differential. The transaxle further includes a pair of synchronizer clutches for establishing four forward gears by selectively coupling the four speed gears to the first intermediate shaft and a synchronizer clutch for establishing one additional forward gear and the reverse gear by selectively coupling the speed gear and reverse gear to the second intermediate shaft.

BACKGROUND OF THE INVENTION

This invention relates generally to manual multi-speed transmissions foruse in motor vehicles. More specifically, the present invention isdirected to a compact manual transaxle having a synchronized reversegear.

Due to increasing consumer demand for front wheel drive vehicles withmore powerful yet fuel-efficient drivetrains, the engine and transaxlemust be efficiently packaged to take advantage of all available spacewithin the engine compartment. Concomitantly, most modern transaxlesmust be capable of providing at least forward five speed ratios. Assuch, minimizing the overall axial length of the transaxle as well asits shaft center distances is of critical importance to the transmissiondesigner. To meet these requirements, various "three-shaft" typetransaxle have been developed. For example, U.S. Pat. No. 4,738,150discloses a five-speed manual transaxle having an input shaft and a pairof countershafts both of which drive the differential which, in turn,drives the axle half-shafts. Gearsets on both countershafts can beselectively engaged to deliver power from the input shaft to thehalf-shafts. Furthermore, U.S. Pat. Nos. 5,385,065 and 5,495,775disclose five-speed transaxles having a synchronized reverse geararrangement.

Accordingly, while such conventional manual transaxle designs attempt toaddress the packaging requirements mentioned above, a need still existsfor development of more compact and robust manual transaxles that canmeet the demands of modern front wheel drive vehicular applications.

SUMMARY OF THE INVENTION

The primary object of the present invention is to provide a multi-speedmanual transaxle that meets the above-noted needs and improves uponconventional designs.

To this end, the present invention is directed to a five-speed manualtransaxle comprised of an input shaft, a first intermediate shaft havinga first transfer gear fixed thereto, a first input gear fixed to theinput shaft, a first speed gear rotatably supported on the firstintermediate shaft and meshed with the first input gear, a second inputgear fixed to the input shaft, a second speed gear rotatably supportedon the first intermediate shaft and meshed with the second input gear, afirst synchronizer clutch for selectively coupling either of the firstand second speed gears to the first intermediate shaft, a third inputgear fixed to the input shaft, a third speed gear rotatably supported onthe first intermediate shaft and meshed with the third input gear, afourth input gear fixed to the input shaft, a fourth speed gearrotatably supported on the first intermediate shaft and meshed with thefourth input gear, a second synchronizer clutch for selectively couplingeither of the third and fourth speed gears to the first intermediateshaft, a second intermediate shaft having a second transfer gear fixedthereto, a fifth input gear fixed to the input shaft, a fifth speed gearrotatably supported on the second intermediate shaft and meshed with thefifth input gear, a reverse gear rotatably supported on the secondintermediate shaft and meshed with the first speed gear, a thirdsynchronizer clutch for selectively coupling either of the fifth speedgear and the reverse gear to the second intermediate shaft, and a finaldrive gear meshed with the first and second transfer gears.

BRIEF DESCRIPTION OF THE DRAWINGS

Further objects, features and advantages of the present invention willbecome apparent to those skilled in the art from studying the followingdescription and the accompanying drawings in which:

FIG. 1 is a sectional view of a five-speed manual transaxle constructedaccording to a preferred embodiment of the present invention;

FIG. 2 is a partial sectional view of the five-speed manual transaxleshown in FIG. 1;

FIG. 3 is a schematic view showing the shaft and gear arrangement forthe transaxle shown in FIG. 1; and

FIG. 4 is a shift gate diagram for the transaxle shown in FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to the drawings, a manual transaxle 10 is shown that isadapted for use in front wheel drive motor vehicles. Transaxle 10 is afive-speed arrangement having all of its forward and reverse gearssynchronized and yet is efficiently packaged to provide a compactgearbox.

With particular reference to FIG. 1, transaxle 10 is shown to include ahousing 12 within which an input shaft 14 is rotatably supported bybearings 16 and 18 for rotation about a first axis "A". As isconventional, input shaft 14 is adapted to be driven through a suitablemanually-released clutch (not shown) by the vehicles's engine. Transaxle10 is also shown to include a first driven or intermediate shaft 20rotatably supported in housing 12 by bearings 22 and 24 for rotationabout second axis "B", a second driven or intermediate shaft 26rotatably supported in housing 12 by bearings 28 and 30 for rotationabout a third axis "C", and a differential 32 supported in housing 12 bybearings 34 and 36 for rotation about a fourth axis "D". As is alsoconventional, the output of differential 32 includes a pair ofaxially-aligned side gears 38 to which axle half-shafts 40 are fixed soas to connect differential 32 to the driving wheels of the motorvehicle. The input to differential 32 is a final drive gear 42 fixed todifferential cage 44 and which is in constant meshed engagement with afirst transfer gear 46 fixed to first intermediate shaft 20 as well aswith a second transfer gear 48 fixed to second intermediate shaft 26. Itwill be appreciated that FIG. 1 is a so-called "unrolled" sectional viewwherein shafts 14, 20, 26 and 40 are all arranged in a single plane.However, in reality, these shafts are compactly arranged parallel toeach other, with no three thereof in a common plane, as shown in FIG. 3.In this manner, the center distance between the shafts can beeffectively minimized.

Transaxle 10 includes a series of constant-mesh gearsets 50, 52, 54, 56,58 and 60 that can be selectively engaged for establishing five forwardspeed ratios as well as a reverse speed ratio between input shaft 14 andfinal drive gear 42. Gearset 50 includes a first input gear 62 fixed toinput shaft 14 and a first speed gear 64 rotatably supported on firstintermediate shaft 20. First speed gear 64 is in constant mesh withfirst input gear 62 for defining a first power transmission path thatcan be selectively engaged to establish a first forward speed ratio.Gearset 52 includes a second input gear 66 fixed to input shaft 14 thatis in constant mesh with a second speed gear 68 rotatably supported onfirst intermediate shaft 20. Thus, gearset 52 functions to define asecond power transmission path that can be selectively engaged toestablish a second forward speed ratio. Gearset 54 includes a thirdinput gear 70 fixed to input shaft 14 that is in constant mesh with athird speed gear 72 rotatably supported on first intermediate shaft 20.As such, gearset 54 functions to define a third power transmission paththat can be selectively engaged to establish a third forward speedratio. Gearset 56 includes a fourth input gear 74 fixed to input shaft14 that is in constant mesh with a fourth speed gear 76 rotatablysupported on first intermediate shaft 20. Thus, gearset 56 functions todefine a fourth power transmission path that can be selectively engagedto establish a fourth forward speed ratio. Gearset 58 includes a fifthinput gear 78 fixed to input shaft 14 that is meshed with a fifth speedgear 80 rotatably supported on second intermediate shaft 26. Gearset 56functions to define a fifth power transmission path that can beselectively engaged to establish a fifth forward speed ratio. Finally,gearset 60 includes a reverse gear 82 rotatably supported on secondintermediate shaft 26 that is meshed with first speed gear 64. Gearset60 defines a sixth power transmission path that can be selectivelyengaged to establish the reverse speed ratio.

To provide means for establishing the various forward and reverse speedratios by selectively engaging one of the available power transmissionpaths, each gearset is associated with a synchronizer clutch. Inparticular, a first synchronizer clutch 84 is operably located betweenfirst and second speed gears 64 and 68 and includes a hub 86 fixed tofirst intermediate shaft 20, a shift sleeve 88 mounted for rotation withand axial sliding movement on hub 86, and a pair of suitableblocker-type synchronizers 90 interposed between shift sleeve 88 andspeed gears 64 and 68. First synchronizer clutch 84 is of thedouble-acting variety such that forward axial movement of shift sleeve88 from its centered neutral position shown is adapted to couple firstspeed gear 64 to first intermediate shaft 20 for establishing the firstforward speed ratio in which first transfer gear 46 drives final drivegear 42. Moreover, rearward axial movement of shift sleeve 88 from itsneutral position is adapted to couple second speed gear 68 to firstintermediate shaft 20 such that first transfer gear 46 drives finaldrive gear 42 at the second forward speed ratio.

To establish the third and fourth forward speed ratios, a secondsynchronizer clutch 92 is located between third and fourth speed gears72 and 76 and includes a hub 94 fixed to first intermediate shaft 20, ashift sleeve 96 mounted for rotation with and axial sliding movement onhub 94, and a pair of blocker-type synchronizers 98 interposed betweenshift sleeve 96, third speed gear 70 and a clutch gear 100 fixed tofourth speed gear 76. Second synchronizer clutch 92 is of thedouble-acting type such that forward axial movement of shift sleeve 96from its neutral centered position shown is adapted to couple thirdspeed gear 72 to first intermediate shaft 20 such that first transfergear 40 drives final drive gear 42 at the third forward speed ratio.Moreover, rearward movement of shift sleeve 96 from its centered neutralposition is adapted to couple fourth speed gear 76 to first intermediateshaft 20 such that first transfer gear 46 drives final drive gear 42 atthe fourth speed ratio.

The fifth forward speed ratio and the reverse speed ratio areestablished via a fourth synchronizer clutch 102, again of thedouble-acting variety, that is located between fifth speed gear 80 andreverse gear 82. Synchronizer clutch 102 includes a hub 104 fixed tosecond intermediate shaft 26, a shift sleeve 106 mounted for rotationwith and axial sliding movement on hub 104, and a pair of blocker-typesynchronizers 108 interposed between shift sleeve 114, reverse gear 82and a clutch gear 110 fixed to fifth speed gear 80. Rearward slidingmovement of shift sleeve 106 from its centered neutral position shown isadapted to couple clutch gear 110 and fifth speed gear 80 to secondintermediate shaft 26 such that second transfer gear 48 drives finaldrive gear 42 at the fifth speed ratio. In contrast, forward slidingmovement of shift sleeve 106 from its neutral position couples it toreverse gear 82 such that reverse gear 82 is releasably coupled tosecond intermediate shaft 26. As such, second transfer gear 48 drivesfinal drive gear 42 at the reverse speed ratio and in the oppositedirection with respect to the normal direction of rotation of finaldrive gear 42 during forward operation. This reversal of directionresults from reverse gear 82 being driven by first speed gear 64 which,in turn, is driven by first input gear 62.

In the first forward gear, torque is delivered from input shaft 14 todifferential 32 through elements 62, 64, 88, 86, 20, 46 and 42. In thesecond forward gear, torque is delivered from input shaft 14 todifferential 32 through elements 66, 68, 88, 86, 20, 46 and 42. In thethird forward gear, torque is delivered from input shaft 14 todifferential 32 through elements 70, 72, 96, 94, 20, 46 and 42. In thefourth forward gear, torque is delivered from input shaft 14 todifferential 32 through elements 74, 76, 96, 94, 20, 46 and 42. In thefifth forward gear, torque is delivered from input shaft 14 todifferential 32 through elements 78, 80, 106, 104, 26, 48 and 42.Finally, in the reverse gear, torque is delivered from input shaft 14 todifferential 32 through elements 62, 64, 82, 106, 104, 26, 48, and 42.

FIG. 3 is a schematic illustration of the arrangement of shafts 14, 20,26 and 40 and of the meshing of the various gearsets. In addition, ashift pattern or gate diagram for transaxle 10 is shown in FIG. 4.Obviously, any suitable shift system coupling each of shift sleeves 88,96, and 106 to a gearshift lever (not shown) for coordinated movement toestablish the various forward and reverse gears can be used withtransaxle 10.

The foregoing discussion discloses and describes a presently preferredembodiment of the present invention. One skilled in the art will readilyrecognize from such discussion, and from the accompanying drawings andclaims, that various changes, modifications and variations can be madetherein without departing from the true spirit and fair scope of theinvention as defined in the following claims.

What is claimed is:
 1. A manual transmission comprising:an input shaft;a first intermediate shaft having a first transfer gear fixed thereto; afirst input gear fixed to said input shaft; a first speed gear rotatablysupported on said first intermediate shaft and meshed with said firstinput gear; a second input gear fixed to said input shaft; a secondspeed gear rotatably supported on said first intermediate shaft andmeshed with said second input gear; a first synchronizer clutch forselectively coupling either of said first and second speed gears to saidfirst intermediate shaft; a third input gear fixed to said input shaft;a third speed gear rotatably supported on said first intermediate shaftand meshed with said third input gear; a fourth input gear fixed to saidinput shaft; a fourth speed gear rotatably supported on said firstintermediate shaft and meshed with said fourth input gear; a secondsynchronizer clutch for selectively coupling either of said third andfourth speed gears to said first intermediate shaft; a secondintermediate shaft having a second transfer gear fixed thereto; a fifthinput gear fixed to said input shaft; a fifth speed gear rotatablysupported on said second intermediate shaft and meshed with said fifthinput gear; a reverse gear rotatably supported on said secondintermediate shaft and meshed with said first speed gear; a thirdsynchronizer clutch for selectively coupling either of said fifth speedgear and said reverse gear to said second intermediate shaft; and afinal drive gear meshed with said first and second transfer gears. 2.The manual transmission of claim 1 further comprising a differentialdriven by said final drive gear.
 3. The manual transmission of claim 1wherein said first synchronizer clutch includes a first shift sleevemounted for rotation with said first intermediate shaft and movable froma neutral position in a first direction for selectively engaging saidfirst speed gear so as to establish a first forward speed ratio, andwherein said first shift sleeve is movable in a second direction fromits neutral position for selectively engaging said second speed gear forestablishing a second forward speed ratio.
 4. The manual transmission ofclaim 3 wherein said second synchronizer clutch includes a second shiftsleeve mounted for rotation with said first intermediate shaft andmovable from a neutral position in a first direction to selectivelyengage said third speed gear for establishing a third speed ratio, andwherein said second shift sleeve is movable from its neutral position ina second direction for selectively engaging said fourth speed gear forestablishing a fourth forward speed ratio.
 5. The manual transmission ofclaim 4 wherein said third synchronizer clutch includes a third shiftsleeve mounted for rotation with said second intermediate shaft andmovable from a neutral position in a first direction for selectivelyengaging said fifth speed gear for establishing a fifth forward speedratio, and wherein said third shift sleeve is movable from said neutralposition in a second direction for selectively engaging said reversegear for establishing a reverse gear ratio.